I am going to assume that you are at a lower level in your aiki-jujitsu trainging. This is the reason for your training slow. If your aiki-jujitsu is done well, then your partner gets seriously crunched. You need to really know what you are doing in your aiki-jujitsu to prevent this from happening while moving at a good pace.

Aikido techniques were changed so that they could be done at a good pace but without crunching your partner. Even with this said, this varies with the style of aikido practiced and the outcome that a dojo/Sensei desires. We do have some techniques that were not changed so you have to be in total control to not crunch your partner.

I cross trained in aiki-jujitsu style. My mentor crunched me with several techniques even though he held back just to teach me the flavor or mentality of the technique being taught.